ROME, 6 November 2002 --
Desertification affects 30 percent of the earth's land
surface, threatening much of the world's productive land.
To deal with this critical problem, scientists are increasingly
looking to Conservation Agriculture, a strategy that helps hold
back the desert, raises yields, increases incomes and allows
farmers to shorten fallow periods.
Recently, with the help of an FAO team led by
Conservation Agriculture expert Josť Benites, 17 participants
from 8 of the world's driest countries gathered for a
course at the Extension and Experimental Station for Irrigation
and Land Techniques, known by its Italian acronym of CO.T.IR.
(Centro per la Sperimentazione delle Tecniche Irrigue ) on
Italy's Adriatic coast. They were joined by experts from
FAO and other institutions in Australia and the United States.
The purpose: hold back the desert. The
means: Conservation Agriculture.
Protecting the land
Conservation Agriculture has three main principles:
minimal soil disturbance and direct planting, maintenance of a
permanent soil cover and judicious choice of crop rotations. It
starts with low-till or no-till agriculture, which makes
ploughing unnecessary. This helps maintain organic matter in
the soil and decreases wind and water erosion.
"In conventional approaches, farmers till
their land in order to sow seeds, but also to aerate the soil,
let in water, get rid of the residues of the previous crop and
expose and destroy harmful pests and organisms,"
explains Mr Benites. "But instead of tilling they can
use seed drills - which create small pockets for seeds while
leaving crop residues in place. These residues protect the land
from wind erosion and promote biological activity, which aerates
the soil just as well."
also increases the amount of organic matter in the ground,
creating a porous soil structure that allows more water to
filter through to the crops' roots - instead of running off
the surface, taking precious soil with it. The result is more
crop and less erosion.
As for pests, they
can be controlled through integrated pest management (IPM), a
technique that controls undesirable organisms by exposing them
to their natural enemies, minimizing the use of chemical
The result of Conservation
Agriculture and IPM is much greater resistance to environmental
degradation, including wind and water erosion. Yields and
incomes rise, fuel and labour are no longer needed for tilling,
and flooding is reduced - indeed, long-vanished springs may
Benefits for dry
Conservation Agriculture is
particularly useful in dry areas, where low rainfall is the main
constraint to growing food, and it may help farmers to switch to
more productive methods. Using Conservation Agriculture enables
the soil to store more of the precipitation that falls during
the fallow period, so farmers can consider more intensive crop
Non-traditional rotations being
considered to exploit Conservation Agriculture in dry areas
include barley, wheat, lentil and chickpea, and also sunflower,
sorghum and millet -- depending on available moisture.
"Conservation Agriculture requires
commitment," says FAO specialist Theodor Friedrich.
"Farmers must change sowing equipment, and they may
need more herbicides and pesticides for the first year or two
while developing integrated pest management. But so far this
technique has paid off on about 60 million hectares worldwide,
much of it in the United States and South America. Some of this
land was degrading fast and would otherwise be nearly useless by
Less has been done in the
fragile dry regions of North Africa and the Middle East. It is
there that Conservation Agriculture is most needed to combat
desertification and increase soil moisture. But it is also the
environment in which it is most difficult to apply.
Breaking a vicious circle
Leaving crop residues on the ground is
crucial to this strategy.But they are often needed for other
purposes, usually animal feed - especially in arid regions,
where organic matter is scarce and valuable. Sheep graze on
barley stubble, for example, and straw is sold as supplementary
feed at lean times of year. Sometimes it is valuable -- lentil
straw can cost more than grain. Saudi Arabia has even imported
But leaving at least some crop
residues in place can still pay by slowing evaporation of
precious soil moisture. This effect is increased in a dry
climate because residues are slower to degrade. Not tilling also
conserves soil moisture, so more organic matter is produced --
outweighing the initial loss of feed or of income from its sale.
CO.T.IR scientists, led by Dr. Michele
Pisante, have proved that this equation works even in drier
areas. In fact, its effects in a dry environment can be
dramatic, increasing wheat yields from 0.5 to 1.5 tons per
hectare. It may also be possible to grow crops annually instead
of every two years in areas with less than 200mm annual
rainfall. Some areas could produce a crop every two years
instead of every six or seven. And Conservation Agriculture can
offer many ways to save soil, water, energy, labour and wear and
tear on equipment.
participants came away from the workshop encouraged and
impressed," says Dr Benites. "There are no
miracles -- Conservation Agriculture requires care and work,
especially in dry areas. It can hold back the desert -- and it
can also make it possible to grow more food. Things don't
get much better than that!"